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Incorporation of Donors in Vapor Grown GaAs

IP.com Disclosure Number: IPCOM000092070D
Original Publication Date: 1968-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Blakeslee, AE: AUTHOR [+2]

Abstract

Ga reacts with SiO(2) at elevated temperatures and liberates free silicon as described in an article by C. N. Cochran and L. M. Foster, J. Electrochem. Soc., 109, 149, 1962. This Si can be transported in the vapor growth system of the drawing and incorporated as an electron donor in growing a crystal of epitaxial GaAs. The concentration of Si can be varied by adjusting the Ga temperature and the rate and extent of flushing with H(2).

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Incorporation of Donors in Vapor Grown GaAs

Ga reacts with SiO(2) at elevated temperatures and liberates free silicon as described in an article by C. N. Cochran and L. M. Foster, J. Electrochem. Soc., 109, 149, 1962. This Si can be transported in the vapor growth system of the drawing and incorporated as an electron donor in growing a crystal of epitaxial GaAs. The concentration of Si can be varied by adjusting the Ga temperature and the rate and extent of flushing with H(2).

The GaAs epitaxial reactor utilizes AsCl(3) and Ga as source materials and pure H(2) as carrier gas to vapor-grow epitaxial layers. H(2) passes continuously through the Ga reservoir to purge it, even though AsCl(3) flow is shut off. The electron concentration n is normally in the low 10/15/ cm/-3/ range for layers grown on <111A> - oriented substrates.

When the Ga reservoir is not being flushed with H(2) between runs, the value of n is higher. If a 1 to 2 week idle period is allowed, n rises to 6-6.5 x 10/16/cm/- 3/. For shorter times between runs, the value of n is lower but not as low, 1-3 x 10/15/cm/-3/, as when the Ga reservoir is continually flushed. Thus the reaction between Ga and quartz, if allowed to proceed without flushing, approaches an equilibrium which corresponds to about 6 x 10/16/ carriers cm/-3/ in the epitaxial layer. This value depends on the Ga temperature. Flushing the Ga with H(2), or some other nonreactive gas, removes some of the Si and consequently lowers the dopin...